Device and method for determining force of a knee joint

ABSTRACT

An orthopaedic surgical device for determining the joint force of a patient&#39;s knee joint includes a tibial paddle shaped to be positioned in the patient&#39;s knee joint and a handle extending from the tibial paddle. The tibial paddle includes a sensor array positioned therein and configured to generate sensor signals indicative of the joint force of the patient&#39;s knee joint. The orthopaedic surgical device also includes a control circuit configured to control a display located on the handle to provide a visual indication of the medial and lateral balance of the joint force.

CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATION

Cross-reference is made to U.S. Utility patent application Ser. No.______, entitled “DEVICE AND METHOD FOR DISPLAYING JOINT FORCE DATA” byJason Sherman, which was filed on Mar. 31, 2009; to U.S. Utility patentapplication Ser. No. ______, entitled “METHOD FOR PERFORMING ANORTHOPAEDIC SURGICAL PROCEDURE” by Mick Rock, which was filed on Mar.31, 2009; to U.S. Utility patent application Ser. No. ______, entitled“DEVICE AND METHOD FOR DETERMINING FORCES OF A PATIENT'S JOINT” by JasonSherman, which was filed on Mar. 31, 2009; and to U.S. Utility patentapplication Ser. No. ______, entitled “SYSTEM AND METHOD FOR DISPLAYINGJOINT FORCE DATA” by Jason Sherman, which was filed on Mar. 31, 2009;the entirety of each of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgicalinstruments and, more particularly, to systems, devices, and methods fordetermining and displaying joint force data.

BACKGROUND

Orthopaedic prostheses are implanted in patients by orthopaedic surgeonsto, for example, correct or otherwise alleviate bone and/or soft tissueloss, trauma damage, and/or deformation of the bone(s) of the patients.Orthopaedic prostheses may replace a portion or the complete joint of apatient. For example, the orthopaedic prosthesis may replace thepatient's knee, hip, shoulder, ankle, or other joint. In the case of aknee replacement, the orthopaedic knee prosthesis may include a tibialtray, a femoral component, and a polymer insert or bearing positionedbetween the tibial tray and the femoral component. In some cases, theknee prosthesis may also include a prosthetic patella component, whichis secured to a posterior side of the patient's surgically-preparedpatella.

During the orthopaedic surgical procedure, a surgeon initially preparesthe patient's bone(s) to receive the orthopaedic prosthesis. Forexample, in the case of a knee replacement orthopaedic surgicalprocedure, the surgeon may resect a portion of the patient's proximaltibia to which the tibia tray will be attached, a portion of patient'sdistal femur to which the femoral component will be attached, and/or aportion of the patient's patella to which the patella component will beattached. During such procedures, the surgeon may attempt to balance orotherwise distribute the joint forces of the patient's joint in order toproduce joint motion that is similar to the motion of a natural joint.To do so, the surgeon may use surgical experience and manually “feel”for the appropriate joint force balance. Additionally or alternatively,the orthopaedic surgeon may use surgical instruments, such as a ligamentbalancer in the case of a knee replacement procedure, to assist in thebalancing or distributing of joint forces.

In addition, in some surgical procedures such as minimally invasiveorthopaedic procedures, surgeons may rely on computer assistedorthopaedic surgery (CAOS) systems to improve the surgeon's ability tosee the operative area such as in minimally invasive orthopaedicprocedures, to improve alignment of bone cut planes, and to improve thereproducibility of such cut planes. Computer assisted orthopaedicsurgery systems assist surgeons in the performance of orthopaedicsurgical procedures by, for example, displaying images illustratingsurgical steps of the surgical procedure being performed and renderedimages of the relevant bones of the patient. Additionally, computerassisted orthopaedic surgery (CAOS) systems provide surgical navigationfor the surgeon by tracking and displaying the position of the patient'sbones, implants, and/or surgical tools.

SUMMARY

According to one aspect, an orthopaedic surgical device may include atibial paddle and a handle secured to the tibial paddle. The tibialpaddle may be shaped to be positioned between a patient's proximal tibiaand distal femur. The orthopaedic surgical device may include a sensorarray positioned in the tibial paddle. The sensor array may include aplurality of pressure sensors configured to generate sensor signalsindicative of a force between the patient's tibia and femur. The handlemay be secured to the tibial paddle and a first display may be securedto an end of the handle. The orthopaedic surgical device may alsoinclude a circuit positioned in the handle. The circuit may beconfigured to receive the sensor signals from the sensor array and tocontrol the display to provide a visual indication of the force betweenthe patient's tibia and femur.

In some embodiments, the tibial paddle may be shaped to rest on asurgically prepared surface of a patient's resected proximal tibia.Additionally, the handle may be secured to the tibial paddle in anorientation such that the paddle is positionable in a patient's kneejoint with the patient's patella in its natural position. For example,the handle may extend from the medial or lateral side of the patient'sknee joint when positioned therein. In some embodiments, the tibialpaddle may include a top paddle housing and a bottom paddle housing. Insuch embodiments, an outer rim of the top paddle housing may be spacedapart from an outer rim of the bottom paddle housing when no force isapplied to the tibial paddle.

In some embodiments, the sensor array may include a medial set ofpressure sensors arranged in a substantially circular pattern and alateral set of pressure sensors arranged in a substantially circularpattern. Additionally, the sensor array may include a first posteriorsensor positioned posteriorly to the medial set of pressure sensors anda first anterior pressure sensor positioned anteriorly to the medial setof pressure sensors. The sensor array may also include a secondposterior sensor positioned posteriorly to the lateral set of pressuresensors and a second anterior pressure sensor positioned anteriorly tothe lateral set of pressure sensors. Additionally, in some embodiments,the plurality of pressure sensors are embodied as capacitive pressuresensors.

In some embodiments, the orthopaedic surgical device may include asecond display secured to the end of the handle. In such embodiments,the handle may include a top handle housing and a bottom handle housing.The first display may be secured to an end of the top handle housing andthe second display may be secured to an end of the bottom handlehousing.

In some embodiments, the first display may be embodied as a plurality oflight emitting diodes. Additionally, the circuit may be configured todetermine a medial force value and a lateral force value based on thesensor signals, determine a relative force value based on the medialforce value and the lateral force value, and control the plurality oflight emitting diodes in a manner to provide an indication of therelative force value. For example, the circuit is configured to sum themedial force value and the lateral force value to determine a totalforce value, determine the relative force value based on the total forcevalue, and activate a light emitting diode of the plurality of lightemitting diodes to provide a visual indication of the relative forcevalue. Additionally, in some embodiments, the first display may beembodied as a plurality of light emitting diodes arranged in amedial-to-lateral extending row. In such embodiments, the circuit may beconfigured to activate a light emitting diode of the plurality of lightemitting diodes in a manner to provide a visual indication of the medialand lateral balance of the force between the patient's tibia and femur.Further, the circuit may include a wireless transmitter configured totransmit data indicative of the force between the patient's tibia andfemur in some embodiments.

According to another aspect, an orthopaedic surgical device may includea planar sensor housing and a handle coupled to the planar sensorhousing and extending thereform. The planar sensor housing may be shapedto be positioned in a knee joint of a patient. A plurality of pressuresensors may be positioned in the planar sensor housing and configured togenerate sensor signals indicative of a joint force of the knee joint.Additionally, a first display may be coupled to the handle. Theorthopaedic surgical device may also include a processor and a memorydevice. The processor may be electrically coupled to the plurality ofpressure sensors. The memory device may have stored therein a pluralityof instructions, which when executed by the processor, cause theprocessor to control the first display to provide a visual indication ofthe joint force of the knee joint.

In some embodiments, the orthopaedic surgical device may also include asecond display coupled to the handle. In such embodiments, the handlemay include a top housing piece and a bottom housing piece. The firstdisplay may be coupled to the top housing piece and the second displaymay be coupled to the bottom housing piece. Additionally, the pluralityof instructions may further cause the processor to control the seconddisplay to provide a visual indication of the joint force of the kneejoint.

Additionally, in some embodiments, the display may be embodied as aplurality of light emitting diodes. In such embodiments, the pluralityof instructions may further cause the processor to determine a medialjoint force value and a lateral joint force value based on the sensorsignals, determine a relative joint force value based on the medialjoint force value and the lateral joint force value, and control theplurality of light emitting diodes in a manner to provide an indicationof the relative joint force value. The plurality of instructions mayalso cause the processor to sum the medial joint force value and thelateral joint force value to determine a total joint force value,determine the relative joint force value based on the total force value,and activate a light emitting diode of the plurality of light emittingdiodes to provide a visual indication of the relative joint force value.Additionally or alternatively, in some embodiments, the display isembodied a plurality of light emitting diodes arranged in amedial-to-lateral extending row. In such embodiments, the plurality ofinstructions may further cause the processor to activate a lightemitting diode of the plurality of light emitting diodes in a manner toprovide a visual indication of the medial and lateral balance of thejoint force.

According to a further aspect, an orthopaedic surgical device mayinclude a tibial paddle shaped to be positioned between a patient'sproximal tibia and distal femur and a handle secured to the tibialpaddle. The orthopaedic surgical device may include a sensor arraypositioned in the tibial paddle. The sensor array may include aplurality of medially located pressure sensors configured to generatesensor signals indicative of a medial force between the patient's tibiaand femur and a plurality of laterally located pressure sensorsconfigured to generate sensor signals indicative of a lateral forcebetween the patient's tibia and femur. The handle may include a tophousing and a bottom housing. The orthopaedic surgical device mayinclude a first plurality of light emitting diodes secured to an end ofthe top housing of the handled and a second plurality of light emittingdiodes secured to an end of the bottom housing of the handle. Theorthopaedic surgical device may also include a circuit positioned in thehandle. The circuit may be configured to activate at least one lightemitting diode of each of the first and second plurality of lightemitting diodes based on the sensor signals to provide a visualindication of the relative balance between the medial force and thelateral force between the patient's tibia and femur.

According to yet a further aspect, a joint distractor for distracting apatient's knee joint may include a cradle configured to receive andsecure a sensor module, a first distractor component movably coupled toa first side of the cradle, and a second distractor component movablycoupled to a second side of the cradle. The first distractor componentmay have a first tibial paddle and a first femoral paddle that extendfrom the first distractor component in an outwardly direction torepetitively contact the tibial paddle of the sensor module and a distalend of a femur of a patient, the first femoral paddle movable withrespect to the first tibial paddle to define a first displacementbetween the patient's tibia and femur. Additionally, the seconddistractor component may have a second tibial paddle and a secondfemoral paddle that extend from the second distractor component in theoutwardly direction to repetitively contact the tibial paddle of thesensor module and the distal end of a femur of a patient, the secondfemoral paddle movable with respect to the second tibial paddle todefine a second displacement between the patient's tibia and femur. Thefirst distractor component and the second distractor component may bemovable with respect to the cradle in the outwardly direction to permitselectively extending one of the distractor components beyond the otherdistractor component in the general direction of extension.

In some embodiments, the cradle may include a locking mechanism tosecure the sensor module in the cradle. Additionally, the firstdistractor component may include a first pair of handles coupled to thefirst tibial and femoral paddles and a first locking mechanismpositioned on an end of the first pair of handles. The first lockingmechanism may be operable to lock the first tibial and femoral paddlesin a first selected position. Additionally, the second distractorcomponent may include a second pair of handles coupled to the tibial andfemoral paddles and a second locking mechanism positioned on an end ofthe second pair of handles. The second locking mechanism may be operableto lock the second tibial and femoral paddles in a second selectedposition.

In some embodiments, the first tibial paddle and the first femoralpaddle may be biased to a contacting position. Additionally, the secondtibial paddle and the second femoral paddle may be biased to acontacting position. Further, in some embodiments, the cradle mayinclude a first locking mechanism to secure the first distractorcomponent at a first selected position of extension and a second lockingmechanism to secure the second distractor component at a second selectedposition of extension.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a simplified diagram of one embodiment of a system formeasuring and displaying joint force data of a patient's joint;

FIG. 2 is a perspective view of one embodiment of a sensor module of thesystem of FIG. 1;

FIG. 3 is a plan view of a top side of the sensor module of FIG. 2;

FIG. 4 is a plan view of a bottom side of the sensor module of FIG. 2;

FIG. 5 is an exploded, perspective view of the sensor module of FIG. 2;

FIG. 6 is an elevation view of an end of the sensor module of FIG. 2;

FIG. 7 is a graph of one embodiment of a display protocol for thedisplays of the sensor module of FIG. 2;

FIG. 8 is a simplified diagram of one embodiment of a sensor array ofthe sensor module of FIG. 2;

FIG. 9 is a simplified diagram of another embodiment of the sensor arrayof the sensor module of FIG. 2;

FIG. 10 is a simplified block diagram of one embodiment of an electricalcircuit of the sensor module of FIG. 2;

FIG. 11 is a simplified flow diagram of one embodiment of a method fordetermining and displaying joint force data that may be executed by thesensor module of FIG. 2;

FIG. 12 is a simplified flow diagram of one embodiment of a method fordisplaying relative joint force data that may be executed by the sensormodule of FIG. 2;

FIG. 13 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 14 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 15 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 16 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 17 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 18 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 19 is a perspective view of another embodiment of a sensor moduleof the system of FIG. 1;

FIG. 20 is a perspective view of one embodiment of a display module ofthe system of FIG. 1;

FIG. 21 is a plan view of the display module of FIG. 20;

FIG. 22 is a simplified block diagram of one embodiment of an electricalcircuit of the display module of FIG. 20;

FIG. 23 is a simplified flow diagram of one embodiment of a method fordisplaying joint force data;

FIGS. 24-26 are illustrative screenshots that may be displayed to a useron the display module of FIG. 20;

FIG. 27 is a perspective view of one embodiment of a joint distactor ofthe system of FIG. 1 having the sensor module of FIG. 2 coupledtherewith;

FIG. 28 is an elevation view of an end of the joint distactor of FIG.27;

FIG. 29 is a top plan view of the joint distactor of FIG. 27;

FIG. 30 is a side elevation view of the joint distactor of FIG. 27;

FIG. 31 is a perspective view of another embodiment of a joint distactorof the system of FIG. 1;

FIG. 32 is a simplified block diagram of one embodiment of a computerassisted surgery system of the system of FIG. 1;

FIG. 33 is a simplified flow diagram of one embodiment of a method forperforming an orthopaedic surgical procedure using the computer assistedsurgery system of FIG. 32;

FIG. 34 is a simplified flow diagram of one embodiment of a method fordetermining and displaying navigation and joint force data that may beexecuted by the computer assisted surgery system of FIG. 32;

FIG. 35 is a simplified flow diagram of one embodiment of a method fordetermining and displaying flexion angle and force data of a patient'sjoint that may be executed by the computer assisted surgery system ofFIG. 32;

FIG. 36 is a simplified flow diagram of one embodiment of a method forperforming an orthopaedic surgical procedure using the system of FIG. 1;

FIG. 37 is a perspective view of a patient's joint in extension duringan orthopaedic surgical procedure using the sensor module of FIG. 2;

FIG. 38 is a perspective view of a patient's joint during an orthopaedicsurgical procedure using the distractor and sensor module of FIG. 20;

FIG. 39 is another perspective view of a patient's joint in flexionduring an orthopaedic surgical procedure using the sensor module of FIG.2;

FIG. 40 is another perspective view of a patient's joint in extensionduring an orthopaedic surgical procedure using the sensor module of FIG.2; and

FIG. 41 is another perspective view of a patient's joint in flexionduring an orthopaedic surgical procedure using the sensor module of FIG.2.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthis disclosure in reference to both the orthopaedic implants describedherein and a patient's natural anatomy. Such terms have well-understoodmeanings in both the study of anatomy and the field of orthopaedics. Useof such anatomical reference terms in the specification and claims isintended to be consistent with their well-understood meanings unlessnoted otherwise.

Referring now to FIG. 1, in one embodiment, a system 10 for determiningand displaying joint forces of a patient's joint during an orthopaedicsurgical procedure includes a sensor module 12, a hand-held displaymodule 14, and a joint distractor 16. The system 10 may also includes acomputer assisted surgery system (CAOS) system 18 in some embodiments.As discussed in more detail below, the sensor module 12 is configured tobe inserted into a patient's joint and provide a visual indication ofthe joint forces to an orthopaedic surgeon. For example, in oneillustrative embodiment, the sensor module 12 provides a visualindication of the relative or balance of the medial-lateral joint forcesof a patient's knee joint. The sensor module 12 may also be configuredto transmit joint force data to the hand-held display module 14 via awireless communication link 20 and/or the computer assisted surgerysystem 18 via a wireless communication link 22. In response, the displaymodule 14 and/or computer assisted surgery system 18 are configured todisplay the joint force data, or data derived therefrom, to anorthopaedic surgeon. Additionally, during the performance of anorthopaedic surgical procedure, such as a total or partial kneearthroplasty procedure, the sensor module 12 may be coupled to the jointdistractor 16 to provide visual indication of the joint forces of thepatient's joint during distraction thereof as discussed below.

Referring now to FIGS. 2-10, the sensor module 12 includes a sensorhousing 30 and a handle 32 coupled to the sensor housing 30. The sensorhousing 30 is sized and shaped to be positioned in a joint of thepatient. In the illustrative embodiment, the sensor housing 30 isembodied as a tibial paddle 34, which is shaped to be positioned in aknee joint of the patient. However, the sensor housing 30 may beconfigured to be used with other joints of the patient in otherembodiments as discussed in more detail below in regard to FIGS. 11 and12.

In use, the tibial paddle 34 is configured to be positioned on aproximal plateau of a patient's resected tibia (see, e.g., FIG. 29-33).As discussed in more detail below, the tibial paddle 34 may be placed incontact with the patient's tibia or may be placed on an interveningplatform or other member. Additionally, the sensor module 12 may be usedon the patient's left or right knee. For example, the sensor module 12may be used on a patient's left knee via a medial surgical approachwherein the tibial paddle 34 is inserted into the patient's left kneejoint via a medial capsular incision. In such position, as discussedbelow, the handle 32 extends out of the medial capsular incision.Alternatively, by simply flipping or turning over the sensor module 12,the module 12 may be used on the patient's left knee via a lateralsurgical approach wherein the tibial paddle 34 is inserted into thepatient's left knee joint via a lateral capsular incision. Again, insuch position, the handle 32 extends out of the lateral capsularincision.

As such, it should be appreciated that sensor module 12 may be used onthe patient's left or right knee using a medial or lateral surgicalapproach. For clarity of description, the sensor module 12 and thesystem 10 are described below with reference to an orthopaedic surgicalprocedure using a medial surgical approach (i.e., using a medialcapsular incision to access the patient's joint). However, it should beappreciated that such description is equally applicable to lateralsurgical approach procedures. As such, some structures are describedusing particular anatomical references (e.g., lateral and medial) withthe understanding that such references would be flipped or switched whenthe module 12 is used in a lateral surgical approach procedure. Forexample, a “medial side” of the tibial paddle 34 becomes a “lateralside” of the tibial paddle 34 when used in a lateral surgical approachprocedure.

The tibial paddle 34 is substantially planar and has a shape generallycorresponding to the shape of the orthopaedic prosthesis to be implantedin the patient. For example, in the illustrative embodiment, the tibialpaddle 34 has a shape generally corresponding to a knee prosthesis of aparticular size. However, in other embodiments as discussed in moredetail below, the paddle 34 (or sensor housing 30) may have a shapegenerally corresponding to other types of orthopedic prostheses such asa hip prosthesis, a shoulder prosthesis, an ankle prosthesis, a spineprosthesis, or a patella prosthesis.

The illustrative tibial paddle 34 includes a curved anterior side 36, acurved lateral side 38, a curved medial side 40, and a curved posteriorside 42, each shaped to approximate the shape a tibial bearing of anorthopaedic knee prosthesis. Again, as discussed above, the lateral side38 and the medial side 40 are lateral and medial sides, respectively, inthose embodiments wherein the sensor module 12 is used in a lateralsurgical approach procedure. The posterior side 42 includes a posteriornotch 44 to allow the tibial paddle 34 to be positioned around the softtissue of the patient's joint such as the posterior cruciate ligament.Additionally, in some embodiments, the posterior notch 44 may alsoprovide a mount for other surgical devices such as a trail post forrotating mobile bearing trails. Further, in some embodiments, theposterior notch 44 may be extended or otherwise have otherconfigurations so as to provide a mount for other orthopaedic surgicaldevices such as fixed and/or mobile tibial trials or the like.

The overall size of the tibial paddle 34 may be selected based on theparticular anatomical structure of the patient. For example, in someembodiments, the tibial paddle 34 may be provided in various sizes toaccommodate patients of varying sizes. It should be appreciated that thegeneral shape and size of the paddle 34 (and sensor housing 30) isdesigned and selected such that the paddle 34 or housing 30 does notsignificantly overhang with respect to the associated bony anatomy ofthe patient such that the paddle 34 or housing 30 nor adversely impingethe surrounding soft tissue.

The handle 32 includes a pair of displays 50, 52 coupled to a first end54 of the handle 32. A second end 56 of the handle 32 opposite the firstend 54 is coupled to the tibial paddle 34. In the illustrativeembodiment of FIG. 2, the handle 32 and tibial paddle 34 aresubstantially monolithic in structure. However, in other embodiments,the tibial paddle 34 may be removably coupled to the handle 32 via asuitable connector or the like.

As illustrated in FIGS. 3 and 4, the handle 32 extends from a side ofthe tibial paddle 34. In the illustrative embodiment, the handle 32extends from the medial side 40 (which is a lateral side when the sensormodule 12 is used in a lateral surgical approach procedure). It shouldbe appreciated that because the handle 32 extends from a side of thepaddle 34, the tibial paddle 34 may be positioned in a knee joint of apatient without the need to sublux or evert the patient's patella. Thatis, the tibial paddle 34 may be properly positioned between thepatient's proximal tibia and distal femur with the patient's patella inthe natural position.

Depending on the particular surgical approach to be used by theorthopedic surgeon, the surgeon may flip the sensor module 12 to theproper orientation such that the tibial paddle 34 is inserted into thepatient's knee joint through the associated capsular incision. In eitherorientation, the handle 32 extends out of the capsular incision and atleast one of the displays 50, 52 is visible to the orthopaedic surgeon.For example, if the orthopaedic surgeon is using a medial surgicalapproach on a patient's left knee, the orthopaedic surgeon may positionthe sensor module 12 in the orientation illustrated in FIG. 3 such thatthe handle 32 extends from the medial side of the patient's knee(through the medial capsular incision) when the tibial paddle 34 isinserted into the knee joint and the display 50 is visible to thesurgeon. Alternatively, if the orthopaedic surgeon is using a lateralsurgical approach on a patient's left knee, the orthopaedic surgeon mayposition the sensor module 12 in the orientation illustrated in FIG. 4such that the handle 32 extends from the lateral side of the patient'sknee (through the lateral capsular incision) when the tibial paddle 34is inserted into the knee joint and the display 52 is visible to thesurgeon.

As discussed above, the sensor module 12 is configured to assist asurgeon during the performance of an orthopaedic surgical procedure. Assuch, the sensor module 12 includes an outer housing 58 formed from abio-compatible material. For example, the outer housing 58 may be formedfrom a bio-compatible plastic or polymer. In one particular embodiment,the sensor module 12 is configured for single-usage and, as such, isprovided in a sterile form. For example, the sensor module 12 may beprovided in a sterile packaging. However, in those embodiments whereinthe tibial paddle 34 is removably coupled to the handle 32, the tibialpaddle 34 may be designed for single-usage and the handle 32 may beconfigured to be reusable via an autoclaving procedure or the like.

As illustrated in FIG. 5, the outer housing 58 of the sensor module 12includes an upper housing 60 and a lower housing 62, which are coupledto each other. In some embodiments, the upper housing 60 and the lowerhousing 62 are mirror images of each other. The upper housing 60includes an upper tibial paddle housing 64 and an upper handle housing66. Similarly, the lower housing 62 includes a lower tibial paddlehousing 68 and a lower handle housing 70.

The display 50 is coupled to the end 54 of the upper housing 60 and thedisplay 52 is coupled to the 54 of the lower housing 62. As illustratedin FIG. 6, the displays 50, 52 are illustratively embodied as arrays oflight emitting diodes. However, in other embodiments, the displays 50,52 may be embodied as other types of displays such as liquid crystaldisplays, segmented displays, and/or the like. In the illustrativeembodiment of FIG. 6, each of the displays 50, 52 includes five separatelight emitting diodes 80, 82, 84, 86, 88. As discussed in more detailbelow, the central light emitting diodes 84 are illuminated when themedial-lateral joint forces of the patient's knee joint areapproximately equal. Additionally, the light emitting diodes 80 and/or82 are illuminated when the medial joint force is greater than thelateral joint force of the patient's knee joint by a predeterminedthreshold amount and the light emitting diodes 86 and 88 are illuminatedwhen the lateral joint force is greater than the medial joint force ofthe patient's knee by the predetermine threshold amount (again, assuminga medial surgical approach). As shown in FIG. 6, the light emittingdiodes 80, 82, 84, 86, 88 of the displays 50, 52 are arranged such thatthe light emitting diodes 80, 82 correspond with the medial side 40 ofthe tibial paddle 34 and the light emitting diodes 86, 88 correspondwith the lateral side 38 of the tibial paddle 34 regardless of theorientation (i.e., regardless of whether the upper housing 60 or thelower housing 62 is facing upwardly).

As discussed in more detail below, the light emitting diodes 80,82, 84,86, 88 may be illuminated according to a predetermined display protocolto provide a visual indication to the surgeon of the relativemedial-lateral joint force balance. By activating or illuminating one ormore of the light emitting diodes 80, 82, 84, 86, 88, an orthopaedicsurgeon may visual determine which side of the patient's joint isexerting a greater amount of force and the general magnitude of suchforce relative to the opposite side of the patient's joint. For example,one illustrative display protocol is presented in graph 170 in FIG. 7.According to the illustrative display protocol 170, only the lightemitting diode 88 is illuminated if the medial-lateral joint forcebalance is 30% medial-70% lateral, respectively, or laterally greater.However, both light emitting diodes 86 and 88 are illuminated if themedial-lateral joint force balance is about 35% medial-65% lateral,respectively. If the medial-lateral joint force balance is about 40%medial-60% lateral, respectively, only the light emitting diode 86 isillumined. If the medial-lateral joint force balance is about 45%medial-55% lateral, respectively, both light emitting diodes 84 and 86are illuminated. If the medial-lateral joint force balance is about 50%medial-50% lateral, only the light emitting diode 84 is illumined. Ifthe medial-lateral joint force balance is about 55% medial-45% lateral,respectively, both light emitting diodes 82 and 84 are illuminated. Ifthe medial-lateral joint force balance is about 60% medial-40% lateral,respectively, only the light emitting diode 82 is illumined. If themedial-lateral joint force balance is about 65% medial-35% lateral,respectively, both light emitting diodes 80 and 82 are illuminated.Additionally, if the medial-lateral joint force balance is 70%medial-30% lateral, respectively, or medially greater, only the lightemitting diode 80 is illuminated. In this way, a visual indication ofthe relative joint force balance of the patient's knee is provided tothe orthopaedic surgeon. Of course, in other embodiments, other displayprotocols may be used to control and illuminate the displays 50, 52.

The sensor module 12 includes a sensor array 90 positioned in the tibialpaddle 34 and communicatively coupled to a control circuit 92 positionedin the handle 32. The sensor array 90 is “sandwiched” between the upperhousing piece 60 and the lower housing piece 62. However, the upperhousing piece 60 and the lower housing piece 62 are spaced apart toallow the sensor array 90 to be compressed by the joint force applied tothe tibial paddle 34. For example, as illustrated in FIG. 6, the upperhousing 64 includes an outer rim 94 and the lower housing 66 includes anouter rim 96, which is spaced apart from the outer rim 94 of the upperhousing 64 by a distance 98. When a joint force is applied to the tibialpaddle 34, the outer rims 94, 96 are moved toward each as the sensorarray 90 is compressed.

The sensor array 90 includes a plurality of pressure sensors or sensorelements 100 configured to generate sensor signals indicative of thejoint force applied to the sensor array 90. In the illustrativeembodiment, the pressure sensors 100 are embodied as capacitive pressuresensors, but may be embodied as other types of sensors in otherembodiments. In the illustrative embodiment, the pressure sensors 100 ofthe sensor array 90 are arranged in a particular configuration. Forexample, in one embodiment as illustrated in FIG. 8, the sensor array 90includes a set of pressure sensors 102, 104, 106, 108 arranged in asubstantially circular pattern and positioned toward the medial side 38of the tibial paddle 34. Additionally, the sensor array 90 includes aset of pressure sensors 112, 114, 116, 118 arranged in a substantiallycircular pattern and positioned toward the lateral side 40 of the tibialpaddle 34. The sensor array 90 also includes a pressure sensor 120positioned toward the anterior side 36 and medial side 38 of the tibialpaddle 34 and a pressure sensor 122 positioned toward the anterior side36 and lateral side 40 of the tibial paddle 34. Additionally, the sensorarray 90 includes a pressure sensor 124 positioned toward the posteriorside 42 and medial side 38 of the tibial paddle 34 and a pressure sensor126 positioned toward the posterior side 42 and lateral side 40 of thetibial paddle 34. Of course, in other embodiments, sensor arrays havingpressure sensors arranged in other configurations may be used. In theillustrative embodiment, the pressure sensors 102, 104, 106, 108 and112, 114, 116, 118 are arranged in a pattern corresponding to the shapeand size of a tibial paddle of the distractor 16 to improve sensitivitythereto as illustrated in and described below in regard to FIG. 27.

The pressure sensors 102, 104, 108, 106, 120, 124 form a medial set ofpressure sensors that generate sensor signals indicative of a medialjoint force component of the joint force of a patient's knee (again,assuming a medial surgical approach). Similarly, the pressure sensors112, 114, 118, 116, 122, 125 form a lateral set of pressure sensors thatgenerate sensor signals indicative of a lateral joint force component ofthe joint force of a patient's knee. Additionally, pressure sensors 102,104, 120 form an anterior-medial set of pressure sensors that generatesensor signals indicative of an anterior-medial joint force component ofthe joint force of a patient's knee. Similarly, the pressure sensors112, 114, 122 form an anterior-lateral set of pressure sensors thatgenerate sensor signals indicative of an anterior-lateral joint forcecomponent of the joint force of a patient's knee. The pressure sensors106, 108, 124 form a posterior-medial set of pressure sensors thatgenerate sensor signals indicative of a posterior-medial joint forcecomponent of the joint force of a patient's knee. Similarly, thepressure sensors 116, 118, 126 form a posterior-lateral set of pressuresensors that generate sensor signals indicative of a posterior-lateraljoint force component of the joint force of a patient's knee.

In other embodiments, the sensor array 90 may include more or fewerpressure sensors. In one particular embodiment, the sensor array 90 mayinclude additional medial and lateral pressure sensors for each condyleof the patient's femur. For example, as illustrated in FIG. 9, thesensor array 90 may include a medial-medial pressure sensor 180, amedial-lateral pressure sensor 182, a lateral-medial pressure sensor184, and lateral-lateral pressure sensor 186. That is, the pressuresensor 180 is configured to sense or measure the medial component of themedial joint force exerted by the patient's medial femoral condyle.Similarly, the pressure sensor 182 is configured to sense or measure thelateral component of the medial joint exerted by the patient's medialfemoral condyle. The pressure sensor 184 is configured to sense ormeasure the medial component of the lateral joint force exerted by thepatient's lateral femoral condyle. Similarly, the pressure sensor 186 isconfigured to sense or measure the lateral component of the lateraljoint exerted by the patient's lateral femoral condyle. The particularshape and size of the pressure sensors 180, 182, 184, 186 may beselected based on size, shape, and positioning of the other pressuresensors of the sensor array 90.

Referring now to FIG. 10, the control circuit 92 includes a processor130 and a memory device 132. The processor 130 may be embodied as anytype of processor configured to perform the functions described herein.For example, the processor 130 may be embodied as a separate integratedcircuit or as a collection of electronic devices. Additionally, theprocessor may be a single or multi-core processor. Although only asingle processor 130 is illustrated in FIG. 10, it should be appreciatedthat in other embodiments, the control circuit 92 may include any numberof additional processors. The memory device 132 may be embodiedread-only memory devices and/or random access memory devices. Forexample, the memory device 132 may be embodied as or otherwise includeelectrically erasable programmable read-only memory devices (EEPROM),dynamic random access memory devices (DRAM), synchronous dynamic randomaccess memory devices (SDRAM), double-data rate dynamic random accessmemory devices (DDR SDRAM), and/or other volatile or non-volatile memorydevices. Additionally, although only a single memory device isillustrated in FIG. 10, in other embodiments, the control circuit 92 mayinclude additional memory devices.

The processor 130 is communicatively coupled to the memory device 132via signal paths 134. The signal paths 134 may be embodied as any typeof signal paths capable of facilitating communication between theprocessor 130 and the memory device 132. For example, the signal paths134 may be embodied as any number of wires, printed circuit boardtraces, via, bus, intervening devices, and/or the like. The processor130 is also communicatively coupled to the sensor array 90 via signalpaths 136. Similar to signal paths 134, the signal paths 136 may beembodied as any type of signal paths capable of facilitatingcommunication between the processor 130 and the sensor array 90including, for example any number of wires, printed circuit boardtraces, via, bus, intervening devices, and/or the like. Additionally,the signal path 136 may include a connector 138 (see FIG. 5) configuredto receive a plug-end 140 of the sensor array 90.

The control circuit 92 also includes a power source 142 and associatedpower control circuitry 144. The power source 142 may be embodied as anumber of batteries sized to fit in the sensor module 12. The powersource 142 is electrically coupled to the power control circuitry 144via signal paths 146 and the power control circuitry 144 is electricallycoupled to the processor 130 and other devices of the control circuit 92via signal paths 148. The signal paths 146, 148 may be embodied as anytype of signal paths including, for example any number of wires, printedcircuit board traces, via, bus, intervening devices, and/or the like.The power circuitry 144 may include power control, distribution, andfiltering circuitry and is configured to provide or distribute powerfrom the power source 142 to the processor 130 and other devices orcomponents of the control circuit 92.

The control circuit 92 also includes user controls 150 communicativelycoupled to the processor 130 via signal paths 152. The user controls 150are embodied as power buttons 154 (see FIG. 6) located on the displays50, 52 and selectable by a user to turn the sensor module 12 on.However, in the illustrative embodiment, the control circuit 92 isconfigured to prevent or otherwise limit the ability of the user fromturning off the sensor module 12 via the power buttons 154 or othercontrols after the sensor module 12 has been turned on. That is, onceturned on, the control circuit 92 is configured to remain on until thepower source 142 is depleted. Such a configuration ensures that thesensor module 12 is used during a single orthopaedic surgical procedureand is not otherwise reusable in multiple procedures.

The signal paths 152 are similar to the signal paths 134 and may beembodied as any type of signal paths capable of facilitatingcommunication between the user controls 150 and the processor 130including, for example any number of wires, printed circuit boardtraces, via, bus, intervening devices, and/or the like.

The control circuit 92 also includes display circuitry 156 for drivingand/or controlling the displays 50, 52. The display circuitry 156 iscommunicatively coupled to the processor 130 via signal paths 158 and tothe displays 50, 52 via signal paths 160. Similar to the signal paths134 discussed above, the signal paths 158, 160 may be embodied as anytype of signal paths capable of facilitating communication between theprocessor 130 and display circuitry 156 and the display circuit 156 anddisplays 50, 52, respectively. For example, the signal paths 158, 160may be embodied as any number of wires, printed circuit board traces,via, bus, intervening devices, and/or the like. As discussed above, inthe illustrative embodiment, the displays 50, 52 are embodied as anarrangement of light emitting diodes 80, 82, 84, 86, 88.

In some embodiments, the sensor module 12 is configured to transmitforce data to the display module 14 and/or computer assisted orthopaedicsurgery (CAOS) system 18. In such embodiments, the control circuitincludes transmitter circuitry 162 and an antenna 164. The transmittercircuitry 162 is communicatively coupled to the processor 130 via signalpaths 166 and to the antenna 164 via signal paths 168. The signal paths166, 168 may be embodied as any type of signal paths capable offacilitating communication between the transmitter circuitry 162 and theprocessor 130 and antenna 164, respectively. For example, similar to thesignal paths 134, the signal paths 166, 168 may be embodied as anynumber of wires, printed circuit board traces, via, bus, interveningdevices, and/or the like. The transmitter circuitry 162 may beconfigured to use any type of wireless communication protocol, standard,or technologies to transmit the joint force data to the display module14 and/or computer assisted orthopaedic surgery (CAOS) system 18. Forexample, the transmitter circuitry 162 may be configured to use awireless networking protocol, a cellular communication protocol such asa code division multiple access (CDMA) protocol, a Bluetooth® protocol,or other wireless communication protocol, standard, or technology.

Referring now to FIGS. 11 and 12, in use, the control circuit 92 isconfigured to execute a method 200 for determining joint force data of apatient's joint and providing a visual indication of the medial-lateralbalance of the patient's joint force. The method 200 begins with block202 in which the control circuit 92 is initialized. For example, inblock 202, the control circuit 92 may perform any number of systemchecks, clear any registers of the processor 130, and/or perform otherinitialization and/or integrity checks. Additionally, in someembodiments, the control circuit 92 is configured to perform ahandshaking routine in block 132 with the hand-held display device 14and/or the computer assisted orthopaedic surgery (CAOS) system 18.During this handshaking routine, the control circuit 92 and thehand-held display device 14 and/or the computer assisted orthopaedicsurgery (CAOS) system 18 may be configured to determine communicationprotocols and/or otherwise establish any type of communicationprocedures for transmitting the joint force data from the sensor module12 to the device 14 or system 18.

In block 206, the control circuit 92 receives the sensor signals or datafrom the sensor array 90. As discussed above, the sensor array 90generates sensor signals indicative of a joint force applied to thetibial paddle 34 when the paddle 34 is positioned in the knee joint of apatient. In block 208, the processor 130 of the control circuit 92determines joint force data based on the sensor signals received fromthe sensor array 90. The joint force data is indicative of the jointforce of the patient's knee. In some embodiments, the joint force datamay be embodied as specific joint force values such as a medial jointforce value, a lateral joint force value, an anterior joint force value,and/or a posterior joint force value, each force being determined inNewtons or similar force measurement unit. In such embodiments, themedial joint force may be determined based on the sensor signals fromthe pressure sensors 102, 104, 106, 108, 120, 124. The lateral jointforce may be determined based on the sensor signals from the pressuresensors 112, 114, 116, 118, 122, 126. The anterior joint force may bebased on the pressure sensor anterior-medial pressure sensors 102, 104,120 and/or the anterior-lateral pressure sensors 112, 114, 122.Additionally, the posterior joint force may be based on the sensorsignals from the posterior-medial pressure sensors 106, 108, 124 and/orthe posterior-lateral sensors 116, 118, 126. Subsequently, in block 210the control circuit 92 controls or otherwise activates the displays 50,52 to display the joint force data determined in block 208. For example,in embodiments wherein one or more specific joint forces are determined,the processor 130 may display the determine joint forces or indiciathereof on the displays 50, 52.

Additionally or alternatively, the control circuit 92 may be configuredto determine the relative medial-lateral joint force balance and displayindicia of such medial-lateral balance on the displays 50, 52 in blocks208, 210. For example, as illustrated in FIG. 12, the control circuit 92may execute a method 220 for determining the relative medial-lateraljoint forces of the patient's joint. In block 222, the control circuit92 determines medial joint force data based on the sensor signalsreceived from the pressure sensors 102, 104, 106, 108, 120, 124.Similarly, in block 224, the control circuit 92 determines lateral jointforce data based on the sensor signals received from the pressuresensors 102, 104, 106, 108, 120, 124The medial and lateral joint forcedata may be embodied as the specific joint force determined in Newtonsor may be embodied as some representation thereof. For example, in someembodiments, the medial and lateral joint force data is measured incapacitance. It should be appreciated that the blocks 222 and 224 may beexecuted in either order.

In block 226, the control circuit 92 determines the relativemedial-lateral balance of the joint force of the patient's joint. To doso, the control circuit 92 compares the medial force data and thelateral force data. For example, in one embodiment, the control circuit92 is configured to determine a total force value by summing the medialforce data and the lateral force data. The control circuit 92subsequently determines a medial percentage value by dividing the medialforce data by the total force value and a lateral percentage value bydividing the lateral force data by the total force value. As such, ifthe medial and lateral forces of a patient's joint are balanced, themedial percentage value would be determined to be about 50% and thelateral percentage value would be determined to be about 50%. Of course,in some embodiments, the control circuit 92 may be configured todetermine only one of the medial and lateral percentage values, theremaining one being known or determined by simple subtraction from 100%.

In block 228, the control circuit 92 activates or controls the displays50, 52 to provide a visual indication of the relative medial-lateralbalance of the joint forces of the patient's joint. For example, inembodiments wherein the displays 50, 52 are embodied as light emittingdiodes, the control circuit 92 is configured to activate or illuminateone or more of the light emitting diodes to provide a visual indicationof the medial-lateral balance of joint forces. The control circuit 92may use any display protocol or pattern of illumination of the lightemitting diodes that provides an appropriate indication to theorthopaedic surgeon of such joint forces.

For example, in one particular embodiment, the control circuit 92 isconfigured to control the displays 50, 52 according to the displayprotocol 170 illustrated in and discussed above in regard to FIG. 7. Insuch embodiments, the control circuit 92 is configured to illuminate thecentrally located light emitting diode 84 of the displays 50, 52 if themedial and lateral joint forces are about equal (i.e., about 50%medial-50% lateral). The control circuit 92 is configured to illuminatethe centrally located light emitting diode 84 and the lateral lightemitting diode 86 if the medial-lateral balance of the joint forces isabout 45% medial-55% lateral, respectively. The control circuit 92 isconfigured to illuminate the lateral light emitting diodes 86, 88 if themedial-lateral balance of the joint forces is about 35% medial-65%lateral, respectively. Additionally, the control circuit 92 isconfigured to illuminate the lateral-most light emitting diode 88 if themedial-lateral balance of the joint forces is about 30% medial-70%lateral (or more lateral), respectively. Similarly, the control circuit92 is configured to illuminate the centrally located light emittingdiode 84 and the medial light emitting diode 82 if the medial-lateralbalance of the joint forces is about 55% medial-45% lateral,respectively. The control circuit 92 is configured to illuminate thelateral light emitting diodes 80, 82 if the medial-lateral balance ofthe joint forces is about 65% medial-35% lateral, respectively.Additionally, the control circuit 92 is configured to illuminate themedial-most light emitting diode 80 if the medial-lateral balance of thejoint forces is about 70% medial-30% lateral (or more medial),respectively.

In this way, sensor module 12 provides a visual indication to theorthopaedic surgeon of the relative medial and lateral forces of thepatient's joint. As discussed in more detail below, the orthopaedicsurgeon can perform balancing procedures on the patient's knee jointwhile monitoring the current balance of the medial and lateral forcesvia the displays 50, 52 to achieve the desired balance for theparticular patient. Additionally, because the sensor module 12 includesa display 50, 52 on either side, the orthopaedic surgeon is provide thevisual indication of the joint forces whether the surgeon is operatingon the patient's left or right knee.

Referring back to FIG. 12, in addition to activating the displays 50, 52to provide the visual notification of the joint forces in block 210, thesensor module 12 may be configured to transmit the joint force data inblock 212. As discussed above, the sensor module 12 may transmit thejoint force data to the hand-held display 14 and/or computer assistedorthopaedic surgery (CAOS) system 18 in block 212. The transmitted jointforce data may be embodied as the specific joint forces measured inNewtons, for example, or may be representations thereof. For example,the sensor signals received from the sensor array 90 or electricalrepresentations of the levels of such signals may be transmitted inblock 212. Regardless, the sensor module 12 is configured to transmitjoint force data that is indicative of the joint forces of the patient'sknee joint to the display 14 and/or the system 18 in block 212.

Referring now to FIGS. 13 and 14, in other embodiments, the handle 32and tibial paddle 34 may be coupled to each other at other orientationsand/or via other intervening structures. For example, as shown in FIG.13, the sensor module 12 may be embodied as a module 232 in which thehandle 32 is coupled to the anterior side 36 of the tibial paddle 34 issome embodiments. In such embodiments, the handle 32 extends anteriorlyfrom the patient's knee joint (e.g., through an anterior capsularincision) when the tibial paddle 34 is inserted therein. Alternatively,as illustrated in FIG. 14, the sensor module 12 may be embodied as amodule 232 in which the handle 32 and the tibial paddle 34 are coupledto each other via a wire 234. The wire 234 may be embodied as aplurality of wires, cables, or other interconnects that communicativelycouple the sensor array 90 positioned in the tibial paddle 34 to thecontrol circuit 92 located in the handle 32. Although the wire 234 isillustratively coupled to the posterior side 36 of the tibial paddle 34in the embodiment of FIG. 14, it should be appreciated that the wire 234may be coupled to the tibial paddle 34 on the lateral side 38, themedial side 40, or the posterior side 42 in other embodiments.

Referring now to FIGS. 15-19, in some embodiments, the sensor module 12may be configured for use with joint's other than the patient's kneejoint. For example, in one embodiment, the sensor module 12 is embodiedas a sensor module 250, which includes a sensor housing 252 and a handle254 connected to the sensor housing 252 via an elongated neck 256. Thehandle 254 is similar to the housing 32 of the sensor module 12 andincludes the control circuit 92 positioned therein and displays 50, 52coupled to an end 258 of the handle 254. The sensor housing 252,however, is configured to be positioned in a ball-and-socket joint ofthe patient such as the patient's hip joint or shoulder joint. As such,the sensor housing 252 is substantially “cup”-shaped and includes aconcave upper housing piece 260 and a corresponding convex lower housingpiece 262. The concave upper housing piece 260 defines an inner recess260, which may receive a portion of an orthopaedic prosthetic orprosthetic trial or an end of a patient's natural or prosthetic boneduring the performance of the orthopaedic surgical procedure. Similar tothe sensor housing 30, the sensor array 90 is positioned in the sensorhousing 252 and is configured to generate sensor signals indicative ofthe joint forces of the patient's relative joint.

In some embodiments, the sensor housing 252 may be detached from thehandle 254, but communicatively coupled therewith, to improve the easeof use of the sensor module 250 with particular joints. For example, asillustrated in FIG. 12, the sensor housing 252 and the handle 254 may bedetached from each other but communicatively coupled via a wire orplurality of wires 266. That is, the sensor array 90 positioned in thesensor housing 252 is communicatively coupled with the control circuit90 positioned in the handle 254.

In another embodiment as illustrated in FIG. 17, the sensor module 12may be embodied as a sensor module 270 configured to be used with aspinal joint of the patient. The sensor module 270 includes a spinalpaddle 272 coupled to the handle 254 via the elongated neck 256. Thespinal paddle 272 is configured to be inserted between the vertebra ofthe patient's spine. In the illustrative embodiment, the paddle 272 hasa substantial curricular shape, but may have other shapes in otherembodiments. The spinal paddle 272 includes a notch 274 configured toreceive a portion of the patient's spinal cord such that the spinalpaddle 272 may be fully inserted into the patient's spine. A sensorarray is included in the spinal paddle 272 to measure or sense the jointforce of the patient's spine. The spinal senor array may have any numberof pressure sensors arranged in a configuration similar to the sensorarray 90 discussed above or in another configuration.

Additionally, in some embodiments as illustrated in FIG. 18, the sensormodule 12 may be embodied as a sensor module 280 configured to be usedwith the patella of the patient's knee joint to measure patellofemoralforces. Similarly to the sensor module 270 discussed above in regard toFIG. 17, the sensor module 280 includes a patella paddle 282 coupled tothe handle 254 via the elongated neck 256. The patella paddle 282 isconfigured to be inserted between the patient's patella and femur. Inthe illustrative embodiment, the paddle 282 has a substantial ovalshape, but may have other shapes in other embodiments. A sensor array isincluded in the patella paddle 282 to measure or sense the force exertedby the patient's patella on the patient's femur. The patella senor arraymay have any number of pressure sensors arranged in a configurationsimilar to the sensor array 90 discussed above or in anotherconfiguration.

Referring now to FIG. 19, in another embodiment, the sensor module 12 isembodied as a sensor module 290 configured to be used with an anklejoint of the patient. The sensor module 290 includes an ankle sensorhousing 292 coupled to handle 254 via a wire 294. The wire 294 may beembodied as a plurality of wires, cables, and/or other interconnects tocommunicatively couple the ankle sensor housing 292 and the controlcircuit 92 located in the handle 254. The ankle sensor housing 292 isconfigured to be inserted in an ankle joint of the patient. In theillustrative embodiment, the ankle sensor housing 292 is shaped as ahalf-cylinder, but may have other shapes in other embodiments. A sensorarray is included in the ankle sensor housing 292 to measure or sensethe patient's ankle joint force. The ankle senor array may have anynumber of pressure sensors arranged in a configuration similar to thesensor array 90 discussed above or in another configuration.

Referring now to FIGS. 20-26, the hand-held display module 14 includes ahousing 300 sized to be held in the hands of an orthopaedic surgeon andused during the performance of an orthopaedic surgical procedure. Inthis way, the display module 14 is configured to be mobile. The displaymodule 14 also includes a display 302 coupled to an upper side 304 ofthe housing 300. A plurality of user input buttons 306, 308, 310 arealso positioned on the upper side 304 of the housing 300 below thedisplay 302. The display module 14 also includes a power button 312. Inthe illustrative embodiment of FIGS. 20-26, the power button 312 ispositioned below the row of input buttons 306, 308, 310, but the buttons306, 308, 310, 312 may be positioned in other configurations and/ororientations in other embodiments. Additionally, the display module 14may include a power-on indicator 314 and a battery state indicator 316located on the upper side 304 of the housing 300.

As discussed above, the hand-held display module 14 is configured to beused with the sensor module 12 to receive joint force data form themodule 12 and display indicia on the display 302 indicative of the jointforces of the patient's joint. Similar to the sensor module 12, thedisplay module 14 may be configured to determine the relativemedial-lateral and/or anterior-posterior balance of the patient's jointforces and display indicia of such balances on the display 302.Additionally, the display module 14 may be configured to determine theanterior-posterior balance of the patient's joint forces and displayindicia of such balances on the display 302. Further, as discussed inmore detail below, the display module 14 may be configured to determinethe specific joint force values (e.g., the medial and lateral jointforces) and display such force values on the display 302. That is, inaddition to an indication of the joint forces relative to each other,the hand-held display module 14 may calculate or otherwise determine themagnitude of the joint force values as measured in a suitable unit offorce such as Newtons. Additionally, the display module 14 may also beconfigured to perform other functions such as store screenshots and dataof the patient's joint forces as displayed on the display 302 anddownload such data to other devices.

As illustrated in FIG. 22, the hand-held display module 14 includes acontrol circuit 320 positioned in the housing 300. The control circuit320 includes a processor 322 and a memory device 324. The processor 322may be embodied as any type of processor configurable to perform thefunctions described herein. For example, the processor 322 may beembodied as a separate integrated circuit or as a collection ofelectronic devices. Additionally, the processor may be a single ormulti-core processors. Although only a single processor 322 isillustrated in FIG. 22, it should be appreciated that in otherembodiments, the control circuit 320 may include any number ofadditional processors. The memory device 324 may be embodied read-onlymemory devices and/or random access memory devices. For example, thememory device 324 may be embodied as or otherwise include electricallyerasable programmable memory devices (EEPROM), dynamic random accessmemory devices (DRAM), synchronous dynamic random access memory devices(SDRAM), double-data rate dynamic random access memory devices (DDRSDRAM), and/or other volatile or non-volatile memory devices.Additionally, although only a single memory device is illustrated inFIG. 22, in other embodiments, the control circuit 320 may includeadditional memory devices.

The processor 322 is communicatively coupled to the memory device 324via signal paths 326. The signal paths 326 may be embodied as any typeof signal paths capable of facilitating communication between theprocessor 322 and the memory device 324. For example, the signal paths326 may be embodied as any number of wires, printed circuit boardtraces, via, bus, intervening devices, and/or the like.

The processor 322 is also communicatively coupled to the user inputbuttons 306, 308, 310 via signal paths 328 and to the power indicator314 via signal paths 344. Similar to signal paths 326, the signal paths328, 344 may be embodied as any type of signal paths capable offacilitating communication between the processor 322 and the user inputbuttons 306, 308, 310 and the power indicator 314, respectively. Forexample, the signal paths 328, 344 may include any number of wires,printed circuit board traces, via, bus, intervening devices, and/or thelike. The user input buttons 306, 308, 310 are software or “soft”buttons, the functionality of each of which may be determined based onthe particular screen displayed on the display 302.

The control circuit 320 also includes an external power input circuitry330, a rechargeable power source 332 such as a rechargeable battery orthe like, and power circuitry 334. The external power input circuitry330 is configured to receive a plug of a charger such as a “wallcharger” and is communicatively coupled to the rechargeable power source332 via signal paths 336. The rechargeable power source 332 iscommunicatively coupled to the power circuitry 334 via signal paths 338.The power circuitry 334 is communicatively coupled to the processor 332via signal paths 340 and to the power button 312 via signal paths 342.The signal paths 336, 338, 340, 342 may be embodied as any type ofsignal paths including, for example any number of wires, printed circuitboard traces, via, bus, intervening devices, and/or the like. The powercircuitry 334 may include power control, distribution, and filteringcircuitry and is configured to provide or distribute power therechargeable power source 332 to the processor 322 and other devices orcomponents of the control circuit 320.

The control circuit 320 also includes display circuitry 346 for drivingand/or controlling the display 392. The display circuitry 346 iscommunicatively coupled to the processor 322 via signal paths 348 and tothe display 302 via signal paths 350. The signal paths 348, 350 may beembodied as any type of signal paths capable of facilitatingcommunication between the processor 322 and display circuitry 346 andthe display circuit 346 and display 302, respectively. For example, thesignal paths 348, 350 may be embodied as any number of wires, printedcircuit board traces, via, bus, intervening devices, and/or the like.

As discussed above, the hand-held display module 14 is configured toreceive joint force data from the sensor module 12. As such the controlcircuit 320 includes receiver circuitry 352 and an antenna 354. Thereceiver circuitry 352 is communicatively coupled to the processor 322via signal paths 356 and to the antenna 354 via signal paths 358. Thesignal paths 356, 358 may be embodied as any type of signal pathscapable of facilitating communication between the receiver circuitry 352and the processor 322 and the antenna 354, respectively. For example,the signal paths 356, 358 may be embodied as any number of wires,printed circuit board traces, via, bus, intervening devices, and/or thelike. The receiver circuitry 352 may be configured to use any type ofwireless communication protocol, standard, or technologies to receivethe joint force data from the sensor module 12. For example, asdiscussed above in regard to the sensor module 12, the display module 14may be configured to a wireless networking protocol, a cellularcommunication protocol such as a code division multiple access (CDMA)protocol, a Bluetooth® protocol, or other wireless communicationprotocol, standard, or technology to communicate with the sensor module12.

The control circuit 320 also includes a universal serial bus (USB)interface 360. The USB interface 360 is communicatively coupled to theprocessor 322 via signal paths 362, which may be embodied as any type ofsignal paths capable of facilitating communication between the USBinterface 360 and the processor 322. For example, the signal paths 362may be embodied as any number of wires, printed circuit board traces,via, bus, intervening devices, and/or the like. The USB interface 360may be used to download data, such as joint force data or screenshotdata, from the display module 14 to another device such as a computer.Additionally, the USB interface 360 may be used to update the softwareor firmware of the control circuit 320.

Referring now to FIGS. 23-26, in use, the control circuit 320 isconfigured to execute a method 400 for determining and displaying jointforce data related to a patient's joint to an orthopaedic surgeon. Themethod 400 begins with block 402 in which the control circuit 320 isinitialized. For example, in block 402, the control circuit 320 mayperform any number of system checks, clear any registers of theprocessor 322, and/or perform other initialization and/or integritychecks. Additionally, in some embodiments, the control circuit 320 isconfigured to perform a handshaking routine in block 404 with the sensormodule 12. During this handshaking routine, the control circuit 320 andthe sensor module 12 may be configured to determine communicationprotocols and/or otherwise establish any type of communicationprocedures for transmitting the joint force data from the sensor module12 to the device module 14.

In block 406, the control circuit 320 receives the joint force data fromthe sensor module 12. As discussed above, the joint force data isindicative of the joint force of the patient's knee as indicated by thesensor signals generated by the sensor array 90 of the sensor module 12.In block 408, the control circuit 320 determines a medial joint forcevalue and a lateral joint force value based on the joint force datareceived in block 406. The medial joint force value is based on thesensor signals received from the pressure sensors 102, 104, 106, 108,120, 124 and the lateral joint force value is based on the sensorsignals received from the pressure sensors 112, 114, 116, 118, 122, 126.In block 410, the control circuit 320 determines an averagemedial/lateral force value based on the medial joint force value and thelateral joint force value determined in block 408. The medial jointforce value, the lateral joint force value, and the average joint forcevalue are subsequently displayed on the display 302 in block 412. Forexample, as illustrated in the screenshots 450, 452, 454 in FIGS. 24,25, and 26, the medial joint force value 430 is displayed toward amedially designated side 460 of the display 302, the lateral joint forcevalue 432 is displayed toward a laterally designated side 462 of thedisplay 302, and the average force value 434 is displayed toward aposterior designated side 464.

In blocks 414, 416, the control circuit 320 determines which mode theorthopaedic surgeon has selected. In the illustrative embodiment, theorthopaedic surgeon may select a first mode in which indicia of only themedial-lateral balance of the patient's joint forces is displayed on thedisplay 302 or a second mode in which may indicia of the medial-lateraland the anterior-posterior balance of the patient's joint forces isdisplayed in the display 302. The user may switch between the two modesby selecting the appropriate user input buttons 306, 308, 310.

If the orthopaedic surgeon has selected the medial-lateral only mode,the method 400 advances to block 418 in which indicia of themedial-lateral balance of the joint forces of the patient's knee aredisplayed on the display 302. To do so, as illustrated in FIG. 24, ascreen display 450 is presented on the display 302 of the display module14. The screen display 450 includes a background image 470, whichillustrative is embodied as an image of a proximal end of a resectedtibia. The control circuit 320 displays a balance bar 472 on thebackground image 470 and an icon 474 on the balance bar 472 in aposition that indicates the relative medial-lateral balance of the jointforces of the patient's joint. For example, in the illustrative screendisplay 450, the icon 474, which is embodied as a rounded rectangle, isdisplayed on the balance bar 472 toward the lateral side 462 of thescreen display 450 (i.e., the side of the display 302 corresponding tothe lateral side of the resected tibia image 470, which illustrativecorresponds to the right side of the display 302). Such positioningindicates that the lateral force component of the total joint force ofthe patient's knee joint is greater than the medial joint forcecomponent. The farther way the icon 474 is located from the center ofthe balance bar 472, the greater the respective medial or lateral forcecomponent. In some embodiments, the balance bar 472 may be calibrated toprovide an indicative of the numerical balance between themedial-lateral forces. Additionally, in some embodiments, the backgroundimage 470 includes an “balanced” icon 476, illustratively embodied as arounded rectangular outline, positioned on the background image 470 suchthat when the icon 474 is located within the boundaries of the icon 476,the medial joint force and the lateral joint force of the patient's kneeare balanced or within a predetermined threshold of each other.

If, however, the orthopaedic surgeon has selected the medial-lateral andanterior-posterior mode, the method 400 advances to block 420 in whichindicia of the medial-lateral and anterior-posterior balance of thejoint forces of the patient's knee are displayed on the display 302. Todo so, as illustrated in FIG. 25, a screen display 452 is presented onthe display 302 of the display module 14. The screen display 450includes the background image 470 on which the balance bar 472, whichillustrative is embodied as an image of a proximal end of a resectedtibia. The control circuit 320 displays a balance bar 472 and icon 474are displayed. Again, the position of the icon 474 on the balance bar472 indicates the relative medial-lateral balance of the joint forces ofthe patient's joint. In addition, however, a medial end 480 of thebalance bar 472 and a lateral end 482 of the balance bar 472 arepositioned based on the corresponding anterior-posterior balance. Forexample, the medial end 480 of the balance bar 472 is positioned towardthe posterior side 464 of the display 302 or the anterior side 466 ofthe display 302 based on the anterior-posterior balance of the medialjoint force. As discussed above, the anterior posterior balance of themedial joint force may be determined based on the sensor signals fromthe pressure sensors 102, 104, 120 for the anterior component and thepressures 106, 108, 124 for the posterior component. Similarly, thelateral end 482 of the balance bar 472 is positioned toward theposterior side 464 of the display 302 or the anterior side 466 of thedisplay 302 based on the anterior-posterior balance of the lateral jointforce. As discussed above, the anterior posterior balance of the lateraljoint force may be determined based on the sensor signals from thepressure sensors 112, 114, 122 for the anterior component and thepressures 116, 118, 126 for the posterior component.

In the illustrative screen display 452 of FIG. 26, the medial end 480 ofthe balance bar 472 is positioned toward the anterior side 466 of thedisplay 302 and the lateral end 482 of the balance bar 472 is positionedtoward the posterior side 464 of the display 302. Such positioningindicates that the anterior force component of the medial forcecomponent is greater than the posterior force component of the medialforce component and that the posterior force component of the lateralforce component is greater than the anterior force component of thelateral force component. The farther way the ends 480, 482 are from theanterior-posterior center, the greater the respective anterior orposterior force component.

Referring now back to FIG. 23, once the appropriate indicia of the jointforce balances have been displayed on the display 302, the controlcircuit 320 determines whether the orthopaedic surgeon would like totake a snapshot of the current display in block 422. The orthopaedicsurgeon may take a screenshot of the display 302 by selecting theappropriate user input button 306, 308, 310. Additionally, thescreenshot is stored in the memory device 324 in block 424 and may besubsequently downloaded from the display module 14.

When a screenshot is stored, an icon 484 appears in the upper rightcorner of the display 302. The icon 484 displays the average force valuethat was measured on the respective stored screenshot. Any number oficons 484 may be displayed on the display 302 to indicate correspondingstored screenshots. Additionally, although only a select number of icons484 may be displayed on the display 302, the control circuit 320 may beconfigured to store any number of screenshots. In addition to the icon484, when a screenshot is stored, a corresponding vertical balance line486 is displayed on the display 302. The balance line 486 provides avisual indication of the medial-lateral balance of the joint forcesdisplayed in the associated stored screenshot. Further, if theorthopaedic surgeon has selected the medial-lateral andanterior-posterior mode, an anterior-posterior balance line 488 isdisplayed on the display 302. The balance line 488 provides a visualindication of the anterior-posterior balance of the medial and lateralforces of the patient's knee joint displayed in the associated storedscreenshot.

Referring now to FIGS. 27-30, as discussed above, the sensor module 12may be coupled to the joint distractor 16 during the performance of anorthopaedic surgical procedure. The joint distractor 16 includes acradle 500 sized and configured to receive the sensor module 12, a firstdistractor component 502 movably coupled to a side 504 of the cradle500, and a second distractor component 506 movably coupled to a side 508of the cradle 500 opposite the side 504. As shown in FIG. 28, the cradle500 includes an opening 509 having a shape corresponding to thecross-sectional shape of the handle 32 of the sensor module 12. Thesensor module 12 may be coupled to the joint distractor 16 by slidingthe sensor module 12 handle-first into the cradle 500. The cradle 500includes a locking mechanism 510 that is operable to lock the sensormodule 12 in the cradle 500.

As illustrated in FIG. 29, each of the distractor components 502, 504includes a mounting bar 512, 514, respectively, which is received in acorresponding slot 516, 518 of the cradle 500. The distractor component502, 504 may be independently moved in an outwardly direction 520 withrespect to the cradle 500 by sliding the respective mounting bars 512,514 in or out off the corresponding slots 516, 518 of the cradle 500. Assuch, either distractor component 502, 504 may be positioned to extendfarther than the other component 502, 504 such that the joint distractoris selectively configured for use with either knee of the patient fromeither a medial or lateral approach. Additionally, the distractorcomponents 502, 504 may be adjusted and positioned based on the shapeand/or size of the sensor housing 30 of the sensor module 12, the shapeand size of the patient's knee, and/or other criteria. In someembodiments, as illustrated in FIG. 29, the mounting bars 512, 514 mayinclude indicia to provide a visual indication of the amount ofextension for each respective distractor component 502, 504. Such visualindication may be viewable by the orthopaedic surgeon via windows 522,524 defined in the cradle 500. When the distractor components 502, 504have been positioned in the desired configuration, the correspondingmounting bars 512, 514 may be locked into position via use of associatedlocking mechanisms 526, 528. When so locked, the distractor components502, 504 are restricted from movement relative to the cradle 500.

As illustrated in FIG. 30, each distractor component 502, 504 includes apaddle set 530, 532 and a pair of handles 534, 536. The paddle set 530of the distractor component 502 includes a tibial paddle 538 and afemoral paddle 540. Similarly, the paddle set 532 of the distractorcomponent 504 includes a tibial paddle 542 and a femoral paddle 544. Thehandles 534 may be operated to move the femoral paddle 540 with respectto the tibial paddle 538 (e.g., upwardly from the tibial paddle 538).Similarly, the handles 536 may be operated to move the femoral paddle544 with respect to the tibial paddle 542 (e.g., upwardly from thetibial paddle 538). The tibial paddles 538, 542 and the femoral paddles540, 544 are biased to a closed or contacting position via springs 546,548, which are illustratively positioned within the handles 534, 536.Additionally, each pair of handles 534, 536 includes an associatedlocking mechanism 550, 552, respectively, which is operable to lock thehandles 534, 536, and thereby the associated tibial paddles 538, 542 andfemoral paddles 540, 544, in a selected position.

In use, the sensor module 12 is positioned in the cradle 500 and securedin place via the locking mechanism 510. Depending on which knee of thepatient will be operated on, the distractor components 502, 504 may bepositioned such that the tibial paddles 538, 542 contact the tibialpaddle 34 of the sensor module 12 as illustrated in FIG. 20. It shouldbe appreciated that the tibial paddles 538, 542 have a substantiallycircular shape generally corresponding to the circular orientation ofthe pressure sensor 102, 104, 106, 108 and the circular orientation ofthe pressure sensors 112, 114, 116, 118. The joint distractor 16 andsensor module 12 may then be inserted into the patient's joint (e.g.,between the proximal end of the patient's tibia and the distal end ofthe patient's femur). The joint distractor 16 may be subsequently usedto distract the patient's joint and, in response to the joint forceapplied to the tibial paddle 34, the sensor module 12 displays themedial-lateral balance of the joint forces of the joint at the selecteddegree of distraction. In this way, an orthopaedic surgeon may use thedistractor 16 and sensor module 12 to adjust and monitor the relativejoint forces of the patient's joint during the performance of theorthopaedic surgical procedure.

In the illustrative embodiment of FIGS. 27-30, the femoral paddles 540,544 pivot with respect to the tibial paddles 538, 542 about a pivotjoint 554 (see FIG. 30). As such, the femoral paddles 540, 544 are movedto an oblique orientation relative to the tibial paddles 538, 542 duringuse. However, in another embodiment as illustrated in FIG. 31, thedistractor 16 may include a four-bar linkage 272 or other mechanismconfigured such that the femoral paddles 540, 544 are moved to asubstantially parallel orientation relative to the tibial paddles 538,542 during use. That is, in such embodiments, the femoral paddles 540,544 and the tibial paddles 538, 542 remain substantially parallel toeach other as the femoral paddles 540, 544 are moved away from thetibial paddles 538, 542. As such, it should be appreciated that thedistractor components 502, 504 are but one illustrative embodiment ofdistractor components to which the cradle 500 may be coupled and, inother embodiments, the cradle 500 may be coupled to other types ofdistractor components configured to operate in manners similar to ordifferent from the distractor components 502, 504.

Referring now to FIGS. 32-35, in some embodiments, the sensor module 12may be configured for use with the computer assisted orthopaedic surgery(CAOS) system 18. In such embodiments, the sensor module 12 isconfigured to transmit the joint force data to the system 18. Asillustrated in FIG. 32, the computer assisted orthopaedic surgery (CAOS)system 18 includes a computer 600, a display 602, and a camera unit 604.The computer 600 is communicatively coupled to the display 602 viasignal paths 606 and to the camera unit 604 via signal paths 608. Thesignal paths 606, 608 may be embodied as any type of signal pathscapable of facilitating electrical communication between the computer600 and the display 602 and the computer 600 and the camera unit 604,respectively. For example, the signal paths may be embodied as anynumber of wires, printed circuit board traces, via, bus, interveningdevices, and/or the like.

The display 602 may be embodied as any type of device such as a liquidcrystal display monitor, a cathode ray tube (CRT) display monitor, orthe like. Additionally, in some embodiments, the display 602 may beembodied as a “heads-up” display. In such embodiments, the signal path606 may be embodied as a wired or wireless signal path. The camera unit604 includes two or more cameras 610, which are positioned such thatreflective arrays 620 coupled to the relevant bones of a patient 612 arein the field of view 614 of the cameras 610.

The computer 600 includes a processor 622, a memory device 624, and areceiver or receiver circuitry 626. The processor 622 may be embodied asany type of processor configurable to perform the functions describedherein. For example, the processor 622 may be embodied as a separateintegrated circuit or as a collection of electronic devices.Additionally, the processor may be a single or multi-core processors.Although only a single processor 622 is illustrated in FIG. 32, itshould be appreciated that in other embodiments, the computer 600 mayinclude any number of additional processors. The memory device 624 maybe embodied read-only memory devices and/or random access memorydevices. For example, the memory device 624 may be embodied as orotherwise include electrically erasable programmable memory devices(EEPROM), dynamic random access memory devices (DRAM), synchronousdynamic random access memory devices (SDRAM), double-data rate dynamicrandom access memory devices (DDR SDRAM), and/or other volatile ornon-volatile memory devices. Additionally, although only a single memorydevice is illustrated in FIG. 32, in other embodiments, the computer 600may include additional memory devices.

The receiver circuitry 626 may be configured to use any type of wirelesscommunication protocol, standard, or technologies to receive the jointforce data from the sensor module 12. For example, as discussed above inregard to the sensor module 12, the computer 600 may be configured tocommunicate using a wireless networking protocol, a cellularcommunication protocol such as a code division multiple access (CDMA)protocol, a Bluetooth® protocol, or other wireless communicationprotocol, standard, or technology to communicate with the sensor module12.

In use, the computer assisted orthopaedic surgery (CAOS) system 18 isconfigured to provide surgical navigation by tracking and displaying theposition of the patient's relevant bony anatomy (e.g., the patient'stibia and femur) to which the reflective arrays 620 are coupled andprovide an amount of surgical procedure walk-through. Additionally, thecomputer assisted orthopaedic surgery (CAOS) system 18 is configured toreceive the joint force data from the sensor module 12 and display thejoint force data or other indicia of the joint forces of the patient'sjoint on the display 602.

To do so, the computer 600 may execute a method 700 for performing anorthopaedic surgical procedure as illustrated in FIG. 33. The method 700begins with block 702 in which the system 18 is initialized. Forexample, in block 702, the computer 600 may perform any number of systemchecks, clear any registers of the processor 622, and/or perform otherinitialization and/or integrity checks. Additionally, any number ofsettings, preferences, and calibrations of the CAOS system 18 may beestablished and performed in block 702. For example, the video settingsof the display 602 may be selected, the language displayed by thecomputer 600 may be chosen, and the touch screen of the display device602, if applicable, may be calibrated in block 702.

In block 704, the selections and preferences of the orthopaedic surgicalprocedure are chosen by the surgeon. Such selections may include thetype of orthopaedic surgical procedure that is to be performed (e.g., atotal knee arthroplasty), the type of orthopaedic implant that will beused (e.g., make, model, size, fixation type, etc.), the sequence ofoperation (e.g., the tibia or the femur first), and the like. Once theorthopaedic surgical procedure has been set up in block 704, the bonesof the patient are registered in block 706. To do so, the reflectivearrays 620 are coupled with the relevant bones of the patient (e.g., thetibia and femur of the patient). Additionally, the contours of suchbones are registered using an appropriate registration tool. To do so, apointer end of such tool is touched to various areas of the bones to beregistered. In response to the registration, the computer 600 displaysrendered images of the bones wherein the location and orientation of thebones are determined based on the reflective arrays coupled therewithand the contours of the bones are determined based on the registeredpoints. Additionally, one or more surgical tools may be registered withthe computer assisted orthopaedic surgery (CAOS) system in block 706.

Once the pertinent bones have been registered in block 706, the computer600, in cooperation with the camera unit 604, displays the images of thesurgical steps of the orthopaedic surgical procedure and associatednavigation data (e.g., location of surgical tools) in block 708. To doso, the process step 708 may include any number of sub-steps in whicheach surgical procedure step is displayed to the orthopaedic surgeon insequential order along with the associated navigational data.Additionally, in block 710 the computer 600 receives joint force datafrom the sensor module 12. As discussed above, the joint force data isindicative of the joint force of the patient's knee as indicated by thesensor signals generated by the sensor array 90 of the sensor module 12.

In block 712, the computer 600 displays the joint force data or otherdata derived therefrom that is indicative of the joint forces of thepatient's joint on the display 602. The computer 600 may be configuredto determine any one or more joint force values based on the joint forcedata in block 712. For example, similar to the hand-held display module14, the computer 600 may be configured to determine a medial joint forcevalue and a lateral joint force value based on the joint force datareceived in block 710. Again, such medial joint force value is based onthe sensor signals received from the pressure sensors 102, 104, 106,108, 120, 124 and the lateral joint force value is based on the sensorsignals received from the pressure sensors 112, 114, 116, 118, 122, 126.The computer 600 may also determine an average medial/lateral forcevalue based on the medial joint force value and the lateral joint forcevalue. In such embodiments, the medial joint force value, the lateraljoint force value, and the average joint force value are subsequentlydisplayed on the display 602 in block 712. In addition, the computer 600may be configured to determine the medial-lateral and/oranterior-posterior balance of the joint forces based on the joint forcedata and display indicia of joint force balance on the display 602 in amanner similar to the hand-held display module 14. For example, thecomputer 600 may present displays similar to the displays 450, 452, 454illustrated in and described above in regard to FIGS. 24, 25, and 26,respectively. in block 412.

In some embodiments, the computer assisted orthopaedic surgery (CAOS)system 18 may be configured to determine and display joint force data onthe display 602 in association with the navigation data. For example,the computer 600 may execute a method 720 for displaying joint forcedata in association with navigation data as illustrated in FIG. 34. Themethod 720 includes a block 722 in which the computer 600 receives jointforce data from the sensor module 12. Again, the joint force data isindicative of the joint force of the patient's knee as indicated by thesensor signals generated by the sensor array 90 of the sensor module 12.In block 724, the computer 600 determines the medial, lateral, and/oraverage joint force values based on the joint force data received inblock 722.

Contemporaneously with the determination of the joint force values inblock 722, the computer 600 determines the location and orientation ofthe patient's relevant bones, such as the patient's femur and tibia inthose embodiments wherein the patient's knee is undergoing anorthopaedic surgical procedure, in block 724. Subsequently, in block728, the computer 600 displays the joint force values determined inblock 722 and the image of the knee joint in block 728. As such, thecomputer 600 may be used to display, for example, the flexion andextension gaps of the medial and lateral condyles of the patient's kneeand contemporaneously display the associated medial, lateral, and/oraverage joint force values of the patient's knee. By monitoring theflexion and extension gaps and the associated joint force values, theorthopaedic surgeon may determine the appropriate amount of gap or jointforce for a particular orthopaedic procedure.

Additionally, in some embodiments, the computer 600 may also beconfigured to determine other anatomical data based on the orientationand position of the patients bones determined in block 726 and displaysuch anatomical data along with the associated joint force values. Forexample, in one embodiment, the computer 600 is configured to determinethe varus/valgus angle of the patient's knee and display the associatedmedial and lateral force values. Additionally, the computer 600 may beconfigured to determine the loaded condyle based on the medial andlateral force values and identify the loaded condyle to the orthopaedicsurgeon on the display 602. Further, in some embodiments, the computer600 may be configured to store the anatomical data, the joint forcevalues, and/or other surgical data such as the implant type size,patient identification data, and/or the like in association with eachother in the memory device 624 or other storage device.

The computer 600 may also be configured to determine and display a graphof flexion angle and associated joint force values in some embodiments.To do so, the computer 600 executes a method 730 as illustrated in FIG.35. The method 730 includes a block 732 in which the computer 600receives joint force data from the sensor module 12. Again, the jointforce data is indicative of the joint force of the patient's knee asindicated by the sensor signals generated by the sensor array 90 of thesensor module 12. In block 734, the computer 600 determines the medial,lateral, and/or average joint force values based on the joint force datareceived in block 732.

Contemporaneously with the determination of the joint force values inblock 732, the computer 600 determines the flexion angle of thepatient's knee in block 736. To do so, the computer 600 determines therelative location of the patient's tibia and femur and determines theflexion angle defined therebetween based on these locations. In block738, the computer 600 stores the joint force data determined in block734 and the flexion angle data determined in block 738. The methodrepeats through blocks 732, 734, 736 to collect data and each, or everypredetermined, flexion angle within a desired range of flexion. Aftersuch data has been collected, the method 730 advances to block 740 inwhich the computer 600 displays a graph of joint force values versusflexion angle. Such graph may include medial and lateral joint forcevalues or may include an average joint force values depending on thepreference of the orthopaedic surgeon.

Referring now to FIGS. 36-41, as discussed above, the sensor module 12may be used during the performance of an orthopaedic surgical procedureto monitor the relative medial-lateral balance of the patient's jointforces. For example, a surgical method 800 for performing a total kneearthroplasty procedure using the sensor module 12 is illustrated in FIG.36. The method 800 begins with block 802 in which the proximal tibia 900of the patient is resected. By resecting the patient's tibia 900, aresected planar surface or plateau is established on the proximal end ofthe tibia. In some embodiments, such as those embodiments wherein thecomputer assisted orthopaedic surgery (CAOS) system 18 is not used, thedistal end of the patient's femur 902 may be resected in block 804.

In block 806, the patient's knee is placed in extension. Subsequently,in block 808, the patient's knee is distracted while in extension andthe joint forces are balanced. To do so, the orthopaedic surgeon mayplace the tibial paddle 34 of the sensor module 12 in the patient's kneejoint. In particular, the tibial paddle 34 is placed on the resectedplateau 850 of the patient's proximal tibia as illustrated in FIG. 37.The tibial paddle 34 may be placed in contact with the patient's tibiaor may be placed on a membrane or other intervening member. As shown inFIG. 37, a spacer block 832 may be used to distract the patient's kneein extension a desired amount. Alternatively, the sensor module 12 maybe coupled to the joint distractor 16, which may be inserted into thepatient's knee joint and operated to distract the joint to the desiredamount. Typically, the patient's knee joint is distracted in extensionan amount necessary to establish a generally rectangular joint gap(i.e., the resected plateau 850 of the patient's tibia is approximatelyparallel with the resected distal end of the patient's femur).

Once a generally rectangular joint gap is established, the orthopaedicsurgeon may balance the medial and lateral joint forces. To do so, theorthopaedic surgeon may perform a ligament release or balancingprocedure to reduce the medial or lateral force of the patient's knee.While so doing, the orthopaedic surgeon may monitor the display 50, 52of the sensor module 12 and/or the hand-held display module 14 todetermine which side to release and when the medial and lateral forcesare approximately equal (e.g., when the middle light emitting diode 84is illuminated). Of course, the orthopaedic surgeon may decide that analternative joint force balance, such as a 45%/55% medial-lateral jointforce balance, is desirable for the particular patient based on suchcriteria as, for example, the age of the patient, the gender of thepatient, the extent of soft tissue damage of the patient's joint, theextent of pre-operative deformity of the patient's joint, etc.Additionally, in some embodiments, such as those embodiments wherein thecomputer assisted orthopaedic surgery (CAOS) system 18 is used, thedistal end of the patient's femur 902 may be resected in block 810.

After the orthopaedic surgeon has properly balanced the medial-lateraljoint forces of the patient's joint in extension, the patient's joint isplaced in flexion in block 812. Subsequently, in block 814, thepatient's knee is distracted while in flexion to the desired balance ofjoint forces. To do so, the orthopaedic surgeon may again place thetibial paddle 34 of the sensor module 12 on the resected plateau 850 ofthe patient's proximal tibia 900. The tibial paddle 34 may be placed incontact with the patient's tibia or may be placed on a membrane or otherintervening member. The orthopaedic surgeon may distract the patient'sknee using, for example, the distractor 16, 560, or other distractor todistract each condyle of the patient's femur differing amounts until themedial and lateral joint forces are approximately equal. By, equalizingthe medial and lateral joint forces, the rotation of the femur isestablished.

After the patient's joint has been distracted to achieve the desiredmedial-lateral joint balance in block 814, a number of additionalresectioning cuts are performed on the patient's distal femur 902 inblock 816. To do so, as illustrated in FIG. 38, a cutting block 860 maybe coupled to the joint distractor 16 and used to perform an anteriorfemoral cut, a posterior femoral cut, and/or chamfer cuts on thepatient's distal femur 902 while the patient's joint is distracted inflexion. In one particular embodiment, the cutting block 860 ispositioned such that the anterior and posterior femoral cuts aresubstantially parallel to the tibial cut while the patient's knee isdistracted in flexion as discussed above. In other embodiments, thecutting block 860 may be positioned such that the angle of the anteriorand posterior femoral cuts correspond to particular angles of theintended implant. As such, the anterior and posterior femoral cuts areperformed with the femur rotated to the desired position. The positionof the cutting block 860 may also be adjusted anteriorly or posteriorlyto set the flexion gap for the orthopaedic implant.

Alternatively, in some embodiments, the rotation of the femur in flexionis predetermined based on anatomical references such as the posteriorcondyles, Whiteside's line, and/or the transepicondylar axis. Theanterior femoral cut, a posterior femoral cut, and/or chamfer cuts areperformed on the patient's distal femur 902 based on the predeterminedrotation of the femur. As illustrated in FIG. 39, a spacer block 854 maybe used to check or verify such femoral cuts. Additionally, ligamentousrelease may be used by the surgeon to balance or define the desiredmedial-lateral joint forces. In such embodiments, the orthopaedicsurgeon may also verify that ligament releases performed in flexion donot adversely affect the joint force balance in extension.

After the final resectioning of the patient's distal femur is complete,the joint force balance of the patient's knee joint is verified in block818. To do so, the orthopaedic surgeon may place the tibial paddle 34 ofthe sensor module 12 on the resected plateau 850 of the patient'sproximal tibia 900 as illustrated in FIGS. 40 and 41. A trial tibialinsert or bearing 862 may be placed on the tibial paddle 34 and a trialfemoral component may be temporarily coupled to the distal end of thepatient's femur 902. The patient's knee joint may then be moved throughvarious degrees of flexion as illustrated in FIG. 41 while theorthopaedic surgeon monitors the associated joint force balance asindicated by the displays 50, 52 of the sensor module 12 to verify thatthe desired joint for balance is maintained throughout flexion of thepatient's joint.

The system 10 has been described above in regard to the measuring,determining, and displaying of joint forces. Such joint forces generallycorrespond to the joint pressure of the patient's joint over a definedarea. As such, it should be appreciated that in other embodiments thesensor module 12, the hand-held display module 14, and the computerassisted surgery system 18 may be configured to measure, determine, anddisplay the pressure of the patient's relative joint in addition to oralternatively to the patient's joint force. For example, in oneembodiment, the pressure of the patient's joint may be determined basedon the known area of each sensor of the pressure sensors or sensorelements 100 of the sensor array 90.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as illustrative and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the devices, systems, and methods describedherein. It will be noted that alternative embodiments of the devices,systems, and methods of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the devices, systems, andmethods that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

1. An orthopaedic surgical device comprising: a tibial paddle shaped tobe positioned between a patient's proximal tibia and distal femur; asensor array positioned in the tibial paddle, the sensor array includinga plurality of pressure sensors configured to generate sensor signalsindicative of a force between the patient's tibia and femur; a handlesecured to the tibial paddle; a first display secured to an end of thehandle; and a circuit positioned in the handle, the circuit configuredto receive the sensor signals from the sensor array and to control thedisplay to provide a visual indication of the force between thepatient's tibia and femur.
 2. The orthopaedic surgical device of claim1, wherein the tibial paddle is shaped to rest on a surgically preparedsurface of a patient's resected proximal tibia.
 3. The orthopaedicsurgical device of claim 1, wherein the handle is secured to the tibialpaddle in an orientation such that the paddle is positionable in apatient's knee joint with the patient's patella in its natural position.4. The orthopaedic surgical device of claim 3, wherein the handleextends from one of the medial side and the lateral side of thepatient's knee joint when positioned therein.
 5. The orthopaedicsurgical device of claim 1, wherein the tibial paddle includes a toppaddle housing and a bottom paddle housing, an outer rim of the toppaddle housing being spaced apart from an outer rim of the bottom paddlehousing when no force is applied to the tibial paddle.
 6. Theorthopaedic surgical device of claim 1, wherein the sensor arrayincludes a medial set of pressure sensors arranged in a substantiallycircular pattern and a lateral set of pressure sensors arranged in asubstantially circular pattern.
 7. The orthopaedic surgical device ofclaim 6, wherein the sensor array includes: a first posterior sensorpositioned posteriorly to the medial set of pressure sensors and a firstanterior pressure sensor positioned anteriorly to the medial set ofpressure sensors, and a second posterior sensor positioned posteriorlyto the lateral set of pressure sensors and a second anterior pressuresensor positioned anteriorly to the lateral set of pressure sensors. 8.The orthopaedic surgical device of claim 1, wherein the plurality ofpressure sensors are capacitive pressure sensors.
 9. The orthopaedicsurgical device of claim 1, further comprising a second display securedto the end of the handle, wherein the handle includes a top handlehousing and a bottom handle housing, the first display being secured toan end of the top handle housing and the second display being secured toan end of the bottom handle housing.
 10. The orthopaedic surgical deviceof claim 1, wherein: the first display comprises a plurality of lightemitting diodes, and the circuit is configured to (i) determine a medialforce value indicative of a medial component of the force between thepatient's tibia and femur, (ii) determine a lateral force valueindicative of a lateral component of the force between the patient'stibia and femur, and (iii) control the plurality of light emittingdiodes in a manner to provide an indication of the medial-lateralbalance of the force between the relative force value.
 11. Theorthopaedic surgical device of claim 10, wherein the circuit isconfigured to: sum the medial force value and the lateral force value todetermine a total force value, determine a medial-lateral force valuebased on the total force value, and activate a light emitting diode ofthe plurality of light emitting diodes to provide a visual indication ofthe medial-lateral force value.
 12. The orthopaedic surgical device ofclaim 1, wherein the first display comprises a plurality of lightemitting diodes arranged in a medial-to-lateral extending row and thecircuit is configured to activate a light emitting diode of theplurality of light emitting diodes in a manner to provide a visualindication of the medial-lateral balance of the force between thepatient's tibia and femur.
 13. The orthopaedic surgical device of claim1, wherein the circuit comprises a wireless transmitter configured totransmit data indicative of the force between the patient's tibia andfemur.
 14. An orthopaedic surgical device comprising: a planar sensorhousing shaped to be positioned in a knee joint of a patient; a handlecoupled to the planar sensor housing and extending therefrom; aplurality of pressure sensors positioned in the planar sensor housingand configured to generate sensor signals indicative of a joint force ofthe knee joint; a first display coupled to the handle; a processorelectrically coupled to the plurality of pressure sensors; and a memorydevice having stored therein a plurality of instructions, which whenexecuted by the processor, cause the processor to control the firstdisplay to provide a visual indication of the joint force of the kneejoint.
 15. The orthopaedic surgical device of claim 14, furthercomprising a second display coupled to the handle, wherein the handleincludes a top housing piece and a bottom housing piece, the firstdisplay being coupled to the top housing piece and the second displaybeing coupled to the bottom housing piece.
 16. The orthopaedic surgicaldevice of claim 14, wherein the plurality of instructions further causethe processor to control the second display to provide a visualindication of the joint force of the knee joint.
 17. The orthopaedicsurgical device of claim 14, wherein: the display comprises a pluralityof light emitting diodes, and the circuit is configured to (i) determinea medial force value indicative of a medial component of the forcebetween the patient's tibia and femur, (ii) determine a lateral forcevalue indicative of a lateral component of the force between thepatient's tibia and femur, and (iii) control the plurality of lightemitting diodes in a manner to provide an indication of themedial-lateral balance of the force between the relative force value.18. The orthopaedic surgical device of claim 17, the plurality ofinstructions further cause the processor to: sum the medial force valueand the lateral force value to determine a total force value, determinea medial-lateral force value based on the total force value, andactivate a light emitting diode of the plurality of light emittingdiodes to provide a visual indication of the medial-lateral force value.19. The orthopaedic surgical device of claim 14, wherein the displaycomprises a plurality of light emitting diodes arranged in amedial-to-lateral extending row and the plurality of instructionsfurther cause the processor to activate a light emitting diode of theplurality of light emitting diodes in a manner to provide a visualindication of the medial-lateral balance of the joint force.
 20. Anorthopaedic surgical device comprising: a tibial paddle shaped to bepositioned between a patient's proximal tibia and distal femur; a sensorarray positioned in the tibial paddle, the sensor array including (i) aplurality of medially located pressure sensors configured to generatesensor signals indicative of a medial force between the patient's tibiaand femur and (ii) a plurality of laterally located pressure sensorsconfigured to generate sensor signals indicative of a lateral forcebetween the patient's tibia and femur; a handle secured to the tibialpaddle, the handle include a top housing and a bottom housing; a firstplurality of light emitting diodes secured to an end of the top housingof the handled, a second plurality of light emitting diodes secured toan end of the bottom housing of the handle; and a circuit positioned inthe handle, the circuit configured to activate at least one lightemitting diode of each of the first and second plurality of lightemitting diodes based on the sensor signals to provide a visualindication of the balance between the medial force and the lateral forcebetween the patient's tibia and femur.
 21. A joint distractor fordistracting a patient's knee joint, the distractor comprising: a cradleconfigured to receive and secure a sensor module; a first distractorcomponent movably coupled to a first side of the cradle, the firstdistractor component having a first tibial paddle and a first femoralpaddle that extend from the first distractor component in an outwardlydirection to repetitively contact the tibial paddle of the sensor moduleand a distal end of a femur of a patient, the first femoral paddlemovable with respect to the first tibial paddle to define a firstdisplacement between the patient's tibia and femur; a second distractorcomponent movably coupled to a second side of the cradle, the seconddistractor component having a second tibial paddle and a second femoralpaddle that extend from the second distractor component in the outwardlydirection to repetitively contact the tibial paddle of the sensor moduleand the distal end of a femur of a patient, the second femoral paddlemovable with respect to the second tibial paddle to define a seconddisplacement between the patient's tibia and femur; wherein the firstdistractor component and the second distractor component are movablewith respect to the cradle in the outwardly direction to permitselectively extending one of the distractor components beyond the otherdistractor component in the general direction of extension.
 22. Thejoint distractor of claim 21, wherein cradle includes a lockingmechanism to secure the sensor module in the cradle.
 23. The jointdistractor of claim 21, wherein: the first distractor component includes(i) a first pair of handles coupled to the first tibial and femoralpaddles and (ii) a first locking mechanism positioned on an end of thefirst pair of handles, the first locking mechanism operable to lock thefirst tibial and femoral paddles in a first selected position, and thesecond distractor component includes (i) a second pair of handlescoupled to the tibial and femoral paddles and (ii) a second lockingmechanism positioned on an end of the second pair of handles, the secondlocking mechanism operable to lock the second tibial and femoral paddlesin a second selected position
 24. The joint distractor of claim 21,wherein: the first tibial paddle and the first femoral paddle are biasedto a contacting position, and the second tibial paddle and the secondfemoral paddle are biased to a contacting position.
 25. The jointdistractor of claim 21, wherein cradle includes a first lockingmechanism to secure the first distractor component at a first selectedposition of extension and a second locking mechanism to secure thesecond distractor component at a second selected position of extension.